大跨度空区顶板失稳临界参数及稳定性分析

Analysis of large-span goaf roof instability critical parameters and stability

为分析复杂空区顶板的稳定性,用力学理论与数值模拟相结合的方法对空区顶板的稳定性进行综合分析。采用简支梁理论、荷载传递交汇线理论、厚跨比法对空区顶板失稳临界参数进行计算,运用FLAC3D数值模拟软件对空区围岩的稳定性进行研究。结果表明,空区顶板的结构参数超出顶板失稳的临界参数的范围,空区处于失稳状态;空区稳定性数值模拟分析得出空区顶板中央位移较大,最大为4.7 cm,空区之间矿柱侧向位移较小;空区顶板最小主应力接近于拉应力状态;在空区顶板、底板及矿柱都有不同程度的塑性区分布,尤其是在矿柱上,分布范围较广,说明空区围岩稳定性较差,空区处于失稳状态比较明显,应及时采取措施治理空区。由此可见,基于FLAC3D的数值模拟分析空区稳定状态,可综合考虑影响空区失稳的因素,较真实反映空区围岩的应力应变及塑性分布状态,具有广泛的适应性。

For the comprehensive analysis of complex goaf roof stability, the method combining clas-sical mechanics and numerical simulation is adopted. With simply supported beam theory, load transfer intersection line theory, and ratio of span and thickness equation, the goaf roof instability critical param-eters are theoretically calculated. The FLAC3D numerical simulation software is utilized to give a study of the surrounding rock stability. Results indicate that the goaf is instable when the roof structure pa-rameters are all higher than the instability critical parameters;according to the goaf roof stability nu-merical simulation analysis, the roof central displacements are larger than the pillar lateral displace-ments with a maximum of 4.7 cm;the goaf roof minimum principle stress is near to the tensile stress;plastic zones are distributed to varying degrees in the goaf roof, floor and pillars, especially widely dis-tributed in the pillars, showing that the goaf surrounding rock is in poor stability and the goaf is obvi-ously instable. Reasonable measures should be taken in time to deal with the goafs. As it shows, the numerical simulation with FLAC3D, which can comprehensively evaluate the instability factors of the goaf, and truly reflect the state of goaf surrounding rock stress-strain and plastic distribution, has widespread applicability.